Prestressed rolling mills

ABSTRACT

THIS DISCLOSURE RELATES TO PRESTRESSED ROLLING MILLS OF THE TYPE IN WHICH THE PASS OPENING BETWEEN THE WORKING ROLLS OF THE MILL IS SET BY SPACING MEANS WHICH ARE DISPLACEABLE RELATIVE TO THE BEARING CHOCKS OF ONE ROLL OF THE MILL AND REST WITH THEIR ENDS ON THE BEARING CHOCKS OF ANOTHER ROLL. THE SPACING MEANS MAY OPERATE EITHER ON THE BEARING CHOCKS OF THE WORKING ROLLS OF THE MILL OR ON THE BEARING CHOCKS OF ANY BACK-UP ROLLS FOR WORKING ROLLS.

Feb-'25 1971 aslMMoNns STAI.

' rnszmssmnomme MILLS Mamal Feb. e. 196e 'EDWIN SIMMONDS United StatesPatent O 3,559,442 PRESTRESSED ROLLING MILLS Edwin Simmonds, Ringwood,and Tom Smith, Parkstone, England, assignors to Loewy RobertsonEngineering Company Limited, Bournemouth, England, a corporation ofGreat Britain Filed Feb. 9, 1968, Ser. No. 704,334 Claims priority,application Great Britain, Feb. 28, 1967, 9,559/ 67 Int. Cl. B21b 31/24U.S. Cl. 72-240 4 Claims ABSTRACT F THE DISCLOSURE This disclosurerelates to prestressed rolling mills of the type in which the passopening between the working rolls of the mill is set by spacing meanswhich are displaceable relative to the bearing chocks of one roll of themill and rest with their ends on the bearing chocks of another roll. Thespacing means may operate either on the bearing chocks of the workingrolls of the mill or on the bearing chocks of any back-up rolls for theworking rolls.

The spacing means generally consist of screw spindles which are rotatedfor their axial displacement in nuts associated with the bearing chocksof the rst roll.

The prestressings means are usually formed by hydrauliccylinder-and-piston units arranged between the bearing chocks of one ofthe two aforementioned rolls and the mill housings.

In known rolling mills of the above-described type, the screw spindlesacting as spacing means were threaded into the bearing chocks of theirst-mentioned roll. With this design, these bearing chocks had to bemade extra large to accommodate the spindles, there being always atleast two spindles for each chock, for reasons of symmetry. Thisincreased the lweight and bulk of the bearing chocks, particularly inthe case where the spacing means operated on the bearing chocks of theback-up rolls of the mill. Moreover, the machining of the threads in thebearing chocks added to their cost.

Furthermore, it is general practice for the bearing chocks to remain onthe rolls when the latter are taken out of the mill, in order to shortenthe time required for the exchange of rolls. This makes it necessary toprovide bearing chocks for each set of rolls. It is therefore desirableto reduce the bulk and cost of these bearing chocks.

It is one of the objects of the present invention to provide aprestressed rolling mill of the above-described type in which thedrawbacks of the known arrangement of spacing means are overcome.

In prestressed rolling mills of the above-described type, means aresometimes provided for automatically controlling the opening of the gapbetween the working rolls so as to eliminate or compensate for anychanges in that opening which might otherwise occur as a consequence ofrandom changes in the roll-separating force. These means may includeload cells for measuring the load in the spacing means, and further loadcells for measuring the prestressing force. A control system having bothtypes of load cells is described in our (accepted) British Pat. No.1,100,581. Heretofore, it was not possible to provide in such a controlsystem means for measuring the rollseparating force. This led to certaincomplications in the control means and in their operation.

It is another object of the present invention to provide ice aprestressed rolling mill of the above-described type having automaticcontrol means for the opening of the gap between the working rolls,which means include instrumentation for the direct measurement of therollseparating force.

The invention is particularly adapted to be incorporated intoprestressed rolling mills of the type having housings in whose windowsthe bearing chocks of the mills are accommodated.

According to the present invention, a prestressed rolling mill compriseshousings, bearing chocks in windows of the housings, hydraulicprestressing means arranged between the housings and the bearing chocksof one mill roll, and spacing means displaceable relative to the bearingchocks of one roll of the mill and resting with their ends on thebearing chocks of another roll, said spacing means being in the form ofscrew spindles threaded into parts of the rolling mill external of thebearing chocks of both said rolls.

With this arrangement, there is no need to increase the bulk and Weightof any of the bearing chocks, nor is it necessary to provide each set ofbearing chocks with its own spacing means.

The parts into which the screw spindles acting as spacing means arethreaded may be in the form of U- or saddle-shaped supports insertedinto the windows of the rolling mill housings. The spindles are thenthreaded into nuts arranged in the leg or side portions of thesesupports, while the bearing chocks of one roll are received between theside or leg portions, the ends of the spindles resting on the bearingchocks of the other mill roll.

Alternatively, the screw spindles acting as spacing means may bethreaded into nuts formed in the mill housings themselves, in which casethe housings have an enlarged part through which the screw spindlespass, the bearing chocks of one roll being received between the enlargedparts, while the spindles rest with their ends on the bearing chocks ofthe other mill roll which is received between the non-enlarged parts ofthe housings.

Load cells may be provided in either form of the invention between theends of the spacing means and the bearing chocks on which the spacingmeans rest, the load cells being adapted to Imeasure the load in thespacing means. Further load cells may be arranged between theprestressing means and the rolling mill housings or the bearing chocksof the adjacent roll, whereby the prestressing force may be measured. Itis then possible to control the prestressing force in the mannerdescribed in our British Pat. No. 1,100,581, whereby the opening of theroll-gap between the working rolls can be automatically controlled, andany changes in that opening which might otherwise occur as a consequenceof random changes in the rollseparating force be eliminated orcompensated.

With the mill according to the invention it is possible to replaceeither of the sets of load cells by load cells arranged between theparts into which the screw spindles acting `as spacing means arethreaded, and the bearing chocks received in these parts. These latterload cells will measure the roll-separating force. By measuring thisforce and the spacing load or the prestressing force, it is possible tocontrol the prestressing force in such a manner that the same resultsare obtained as in the case of the control system according to ourBritish Pat. No. 1,100,- 581, having regard to the fact that at alltimes in a mill of the type described, the prestressing force is equalto the sum of the spacing load and the roll-separating force.

Two embodiments of the invention will now be described by way of examplewith reference to FIGS. l and 3 2 and of the accompanying drawings, inwhich lateral views, partly in section of horizontal prestressed rollingmills in which the invention is incorporated are illustrated.

The rolling mills according to FIGS. l and 2 are both of the four-hightype. Each mill comprises on each side thereof a housing 2 with a window4 for receiving therein upper and lower bearing chocks 6 and 8 for upperand lower backing rolls 10 and 12 respectively. Bearing chocks 14 and 16for upper and lower work rolls 18 and 20 respectively are nested in thechocks of the associated backing rolls. Hydraulic balancing units 22 arearranged between the back-up chocks 6 and 8, and hydraulic balancingunits 24 are arranged between the work roll chocks 14 and 16. Hydraulicprestressing units 26, each comprising a cylinder 28 and a ram 30, arearranged between the lower transverse parts 32 of the housings 2 and theunderside of the lower back-up chocks 8.

According to FIG. 1, upper back-up chocks 6 are received in U- orsaddle-shaped supports 34 whose downwardly depending side or legportions 36 embrace the chocks 6 at both their sides, while the bridgeportion 38 of the supports 34 extend across the upper side of the chocks6 and along the insides of the upper transverse parts 40 of the housings2. In the embodiment shown in FIG. 1, the supports 34 fit closely intothe windows 4, and their side or leg portions 36 contact the sides ofthe chocks 6. The top of these chocks is slightly spaced-apart from thebridge portion 38 for a purpose to be specified later.

Spacing means for setting the pass opening between the working rolls 18and 20 are provided in the form of vertical spindles 42 which freelyextend through the transverse top part 40 and most of the leg portions36 of the support 34 and are screw-threaded at their ends into nuts 44.The latter are secured to the leg portions 36 so that rotation of thespindles 42 moves those spindles axially relative to the chocks 6.

The spindles 42 rest with their lower ends on the lower back-up chocks8, the latter being made of greater width than the upper back-up chocks6 for that purpose. The spindles are preferably arranged in pairs oneach back-up chock 6, the two spindles of a pair being disposed atpposite sides of the common axial plane of the mill rolls andsymmetrically with respect to that plane. Pressure pads 46 are arrangedbelow the lower ends of the spindles 42. The latter are driven at theirupper ends through splined connections with bevel gears 48 and a commonshaft 50, so that the spindles 42 rotate in unison. Further means, notshown, may be provided to ensure synchronism between the rotation of thespindles 42 of one back-up chock 6 with those of the spindles of theother back-up chock. The shaft 50 is driven by an electric motor, notshown.

When it is desired to adjust the pass opening between the working rolls18 and 20, the spindles 42 are simultaneously rotated through theafore-described drive, whereby they are raised or lowered relative tothe upper back-up chocks 6 in accordance with the direction of therotation of the spindles. The lower back-up chock 8 with the lowerback-up roll 12, as well as the lower work roll chock 16 with the lowerwork roll 20, follow the movements of the spindles 42 as the chocks 8are kept in contact with the lower ends of the spindles 42 at all timesby means of the hydraulic units 26. If desired, the pressure in theseunits may be lowered during the adjustment of the spindles 42.

In the embodiment of FIG. 2, corresponding parts have been denoted bythe same reference numbers as in FIG. l. In the case of FIG. 2, thespindles 42 are arranged in the housings 2, the latter having to thisend internal enlargements through which the spindles pass. There is thenn0 necessity for providing separate supports 34. Otherwise, thearrangements of the parts of the rolling mill shown in FIG. 2 is similarto that of FIG. 1.

In both cases, spindles 42 are arranged in parts external of any bearingchocks of the rolling mill. It is therefore possible to exchange therolls, together with their bearing chocks, without having to manipulatethe spindles. Furthermore, the upper back-up chocks 6 can be madelighter and more cheaply. Saving weight is important because thisback-up chock has to be lifted out of the mill each time the workingrolls 18 and 20 are exchanged, while the lower back-up chocks 8 mayremain in place.

It is understood that both sides of the rolling mill are identical andthat each housing 2 thereof has either separate supports 34 for theupper back-up chocks 6 (FIG. 1) or that each housing 2 has enlargedparts (FIG. 2).

If desired, automatic control means may be provided in either of therolling mills of FIG. 1 or FIG. 2 for ensuring that the pass openingbetween the working rolls 18, 20 is not changed by any of the randomchanges of the roll-separating force which occur during a rollingoperation, thereby ensuring a rolled product of uniform thickness fromend to end. Load cells 52 are then provided between the pressure pads 46and the lower back-up chocks 8. These load cells are preferably of atype in which the measurements are transformed into electric signals andin which there is a linear relationship between the loads registered andthe signals emitted. The load cells 52 indicate the load S-the so-calledspacing load-in the spindles 42, this load being at all times thedifference between the prestressing force P and the roll-separatingforce R. By providing the control system described in our British Pat.No. 955,164, it is possible to eliminate those changes in thepass-opening between the work rolls 18, 20 caused by changes in theroll-separating force R and attributable to the chock spring of themill.

When it is desired to take into account changes attributable both tochock spring and to roll spring, load cells, not shown here, may bepositioned between the prestressing units 30 and the lower back-upchocks 8, whereby the prestressing force P is measured. Control of theprestressing force can then be effected by the system described in ourBritish Pat. No. 1,100,581.

Alternatively, load cells 54 may be placed between the upper back-upchocks 6 and the bridge parts 38 of the supports 34 (FIG. 1) or betweenthe back-up chocks 6 and the upper transverse parts 40 of the millhousings (FIG. 2). These load cells measure the roll-separating force R.It is then possible to dispense either with the load cells not shownhere and arranged next to the prestressing units 30, or with the loadcells 52 which measure the spacing load. In the first case, control ofthe prestressing force is effected by the measurement of theroll-separating force R and the spacing load S; in the second case, bythe measurement of the roll-separating force R and the prestressingforce P. As the prestressing force P is at all times equal to the sum ofthe spacing load S and the rollseparating force R, the control methodsapplicable in the case of measurements of S and R or P and R may bereadily obtained by substitution of R=PS in the equations given in ourBritish Pat. No. 1,100,581.

We claim:

1. A prestressed rolling mill comprising housings, rolls arranged atopposite Sides of the gap through which the rolled articles pass,bearing chocks for supporting said rolls in said housings and adjustableroll-spacing means comprising threaded spindles, arranged on both sidesof the common axial plane of said rolls, said spindles being mounted inthe housings and extending alongside and outwardly of the bearing chocksof a first roll at one side of said gap and resting with their ends onthe bearing chocks of a second roll at the opposite side of said gap,the mating threads for said spindles being provided on parts of the millexternally of the bearing chocks of both said rolls and embracing thebearing chocks of said rst roll.

2. A prestressed rolling `mill according to claim 1 in which the partsof the housing provided with the threads for said spindles are U-shaped,the legs of said U-shaped parts being provided with said threads andstraddling 5 the bearing chocks of said first roll and the bridgeportion of said U-shaped parts being inserted between said bearingchocks and said housings.

3. A prestressed rolling mill according to claim 1 in which load cellsare provided between the ends of said spindles and the bearing chocks ofsaid second roll.

4. A prestressing mill according to claim 2, in which the bearing chocksof said first roll are narrower than the bearing chocks of said secondroll so that the bearing chocks of said second roll have shouldersprojecting beyond the width of the bearing chocks of said rst roll, andin which the spindle portions rest with their ends on said shoulders andpass outside and alongside the bearing chocks of said first roll.

6 References Cited UNITED STATES PATENTS 4/ 1966 Cozzo 72-240 4/ 1969Elton 72-240 FOREIGN PATENTS l/1964 Australia.

U.S. C1. X.R.

